| Summary: | Thesis (Ph.D.)--University of Washington, 2014 The snow crab ( Chionoecetes opilio ) population in the eastern Bering Sea historically supported a lucrative fishery, but was declared overfished in 1999. The subsequent rebuilding plan did not rebuild the fishery in the time specified, and low recruitment over this period likely contributed to the failure. A key component of the rebuilding plan for snow crab was the stock assessment on which management advice was based. In common with all stock assessments, there are numerous potential sources of uncertainty associated with the snow crab assessment, but it is not clear which source is most influential. Consequently, it is unclear how research should be focused and how management should respond to these uncertainties. This dissertation: 1) examines the influence of uncertainty on the ability of the assessment method to estimate quantities important to management, 2) reviews existing information on possible environmental drivers of recruitment, 3) presents an `oscillating control' model that links recruitment to changes in the Pacific Decadal Oscillation (PDO), 4) evaluates management strategies given recruitment dynamics driven by the PDO and 5) explores the influence of spatial structure the snow crab population on assessment. The estimation ability of the assessment method was determined using management strategy evaluation methods. The results of the evaluation allowed biases that may have influenced the ability of the management strategy to rebuild the stock to be identified. When all assumptions are correct, the assessment method provides good estimates of management quantities, including mature male biomass and the overfishing level. Data to reduce uncertainty around growth and natural mortality would be most beneficial to improving confidence in assessment estimates of mature male biomass. The 1988/89 regime shift in the North Pacific appears to have shifted the drivers of recruitment dynamics from female spawning biomass to environmental influences ...
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